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4 Cards in this Set
- Front
- Back
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Enthalpy (H) |
The heat content of a substance at constant pressure |
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Change in enthalpy (∆H) |
The change in the enthalpy that occurs during a chemical reaction ∆H = Hfinal - Hinitial - ∆H energy was given off (exothermic). +∆H energy was absorbed (endothermic). |
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Two ways to provide Enthalpies of reactions |
1. They can be expressed in energy per mole of a reactant or a product. 2. The enthalpy change can be given along with a balanced equation where the equation tells you the relative number of moles. |
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How much heat is evolved if 454 g of propane is burned given the following: C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(l) ΔH = -2220 kJ? |
Part I: Determine the moles of propane present in the sample. 454 g C3H8 x (1 mole C3H8 / 44.0 g C3H8) = 10.318 moles C3H8 Part II: Using the equation and the ΔH, determine the amount of heat evolved from this sample. 10.318 moles C3H8 x (-2220 kJ / 1 mol C3H8) = -22900 kJ |
